For quite some time now electric fuel pumps have been utilized to furnish hydrocarbon fuels to internal combustion engines either through carburetors, or fuel injectors, in an engine manifold. The furnishing of fuel under pressure has supplanted the vacuum systems and fuel pumps in the engine compartment and has assisted in the starting characteristics of the modern day vehicles.
The fuel pumps are quite generally mounted in the fuel tank at the rear of a vehicle. In some instances fuel canisters are used in these fuel tanks to house the fuel pump and receive fuel return flow from a pressure regulator valve in the fuel system.
The location of these pumps in a tank near or at the rear of a vehicle passenger compartment has resulted in concerted efforts to reduce the vibration and noise of an operating pump which otherwise might prove to be an annoyance to passengers.
These efforts involve mounting the pump in a manner to reduce vibration and operating noise and also careful pump design to reduce cavitation and flashback which results in pump noise. Flexible pump mounting is illustrated in a copending patent application, Ser. No. 07/312,259, filed Feb. 17, 1989 and U.S. Pat. No. 4,780,063 dated Oct. 25, 1988. Pump design is illustrated in U.S. Pat. No. 4,697,995 dated Oct. 6, 1987.
The present invention is directed to a pump design to reduce transmission of unbalance or vibration from a pump to the surrounding mount or fuel tank. Pump armatures are usually mounted on a shaft which is mounted in a sealed pump housing. An armature may sometimes be not perfectly balanced so that there is a certain amount of "run-out" as the armature rotates. In addition, starting and stopping of a pump may cause torque and side motion.
In the solution proposed by the present invention, one end of the revolving pump shaft is mounted in one end of a flexible spindle so that any run-out is absorbed by the spindle and not transmitted to the pump enclosure itself. In addition, the spindle can be contained in a dead-end chamber surrounding the spindle, the open end of the chamber being baffled and serving to modulate the pulses of the pump output.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details to enable persons skilled in the art to practice the invention all in connection with the best mode presently contemplated for the invention.